In recent decades, fuel cell technology has been undergoing revolutionary developments, with fundamental progress being the replacement of electrolyte solutions with polymer electrolytes, making the device more compact in size and higher in power density. Nowadays, acidic polymer electrolytes, typically Nafion, are widely used. Despite great success, fuel cells based on acidic polyelectrolyte still depend heavily on noble metal catalysts, predominantly platinum (Pt), thus increasing the cost and hampering the widespread application of fuel cells. Here, we report a type of polymer electrolyte fuel cells (PEFC) employing a hydroxide ionconductive polymer, quaternary ammonium polysulphone, as alkaline electrolyte and nonprecious metals, chromium-decorated nickel and silver, as the catalyst for the negative and positive electrodes, respectively. In addition to the development of a high-performance alkaline polymer electrolyte particularly suitable for fuel cells, key progress has been achieved in catalyst tailoring: The surface electronic structure of nickel has been tuned to suppress selectively the surface oxidative passivation with retained activity toward hydrogen oxidation. This report of a H2-O2 PEFC completely free from noble metal catalysts in both the positive and negative electrodes represents an important advancement in the research and development of fuel cells.nonprecious metals ͉ hydrogen oxidation ͉ oxygen reduction F uel cells have been recognized as an alternative powergeneration technique for the future in both mobile and stationary uses (1, 2). After decades of evolution, fuel cells of various types have been developed (2), such as alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), solid oxide fuel cell (SOFC), and polymer electrolyte fuel cell (PEFC). Among them, PEFC has been the most developed one in the past 2 decades (3), featuring rapid startup and high power density particularly suitable for vehicle applications (1-3).Compared with the aqueous electrolytes traditionally used in low-temperature fuel cells, polymer electrolytes completely eliminate the problems caused by electrolyte leakage and can effectively separate the fuels (such as hydrogen) and the oxidant (oxygen) with a thin film of a few tens of microns in thickness. For decades, the commonly used polymer electrolytes have been limited to proton exchange membranes, typically Nafion . Nowadays, many Nafion-based fuel cell systems of different sizes are being demonstrated or tested on a variety of applications across the world. Although they are promising, the Nafion-based fuel cells still face a number of obstacles to commercialization, one of which has been the severe dependence of catalysts on platinum (Pt), an expensive and scarce resource in the earth. Such dependence stems from the strong acidic nature of the protonexchange membrane; and thermodynamically, only noble metals can be relatively stable in this corrosive environment. Despite tremendous efforts devoted to the search for non-...
Although the proton exchange membrane fuel cell (PEMFC) has made great progress in recent decades, its commercialization has been hindered by a number of factors, among which is the total dependence on Pt‐based catalysts. Alkaline polymer electrolyte fuel cells (APEFCs) have been increasingly recognized as a solution to overcome the dependence on noble metal catalysts. In principle, APEFCs combine the advantages of and alkaline fuel cell (AFC) and a PEMFC: there is no need for noble metal catalysts and they are free of carbonate precipitates that would break the waterproofing in the AFC cathode. However, the performance of most alkaline polyelectrolytes can still not fulfill the requirement of fuel cell operations. In the present work, detailed information about the synthesis and physicochemical properties of the quaternary ammonia polysulfone (QAPS), a high‐performance alkaline polymer electrolyte that has been successfully applied in the authors' previous work to demonstrate an APEFC completely free from noble metal catalysts (S. Lu, J. Pan, A. Huang, L. Zhuang, J. Lu, Proc. Natl. Acad. Sci. USA 2008, 105, 20611), is reported. Monitored by NMR analysis, the synthetic process of QAPS is seen to be simple and efficient. The chemical and thermal stability, as well as the mechanical strength of the synthetic QAPS membrane, are outstanding in comparison to commercial anion‐exchange membranes. The ionic conductivity of QAPS at room temperature is measured to be on the order of 10−2 S cm−1. Such good mechanical and conducting performances can be attributed to the superior microstructure of the polyelectrolyte, which features interconnected ionic channels in tens of nanometers diameter, as revealed by HRTEM observations. The electrochemical behavior at the Pt/QAPS interface reveals the strong alkaline nature of this polyelectrolyte, and the preliminary fuel cell test verifies the feasibility of QAPS for fuel cell applications.
Alloying 3d transition metals with Pt has been discovered as an effective strategy to boost the catalytic activity in oxygen reduction reaction (ORR), which, however, often raises the insufficient catalyst durability issue due to rapid leaching of the 3d metal elements. To overcome this issue and realize enhancements in both the activity and the durability properties, here we report a new catalytic structure based on PtGa ultrathin alloy nanowires (NWs), which feature an unconventional strong p−d hybridization interaction. Relative to commercial Pt catalyst, the optimum Pt 4.31 Ga NWs catalyst exhibited 10.5-and 12.1-fold enhancement in the ORR mass activity and specific activity, respectively. Particularly, the Pt 4.31 Ga NWs catalyst showed only 15.8% loss in the mass activity after 30 000 cycles of durability test, as compared to a big decrease of 79.6% for the commercial Pt catalyst. Our mechanistic studies find a strong p−d hybridization interaction between Ga and Pt that accounts for the improved ORR performance via synergistically optimizing the surface electronic structure, enhancing the oxidation resistance of Pt, and suppressing the leaching of lattice Ga. We believe this work provides new perspectives to design active and durable electrocatalysts toward ORR.
distribution make it difficult to meet the demand of large-scale energy storage device with low cost and high performance. [1,2] Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs), as "post Li-ion batteries," share similar operation principles and battery device to LIBs. [3-8] In recent years, they have drawn great attention due to obvious advantages such as high sodium/potassium abundance, even distribution and low cost, which are ideal candidates for high-performance secondary batteries in large-scale storage systems. With the continuous development of clean energy technology (including wind energy, solar energy, biomass energy, geotherm energy and water energy) and increasing proportion of clean power generation in the total power generation (the installed capacity of wind energy and solar energy may reach 7059 GW accounting for 49.21% in 2040), smart management of intermittent electricity is increasingly important. [9,10] The generated intermittent electricity needs to be regulated by a smart grid, which can be stored in high-performance SIBs/PIBs during low demand periods and released during peak demand periods, such as electricity supply of slow electric vehicles, residences, manufactories and remote area (Figure 1). [11-13] In some remote mountainous areas, there is no electricity transmission line and therefore SIBs/PIBs energy storage system can provide a continuous electricity supply as a power source. When electricity power is in short supply or out of power, SIBs/PIBs energy storage systems can provide considerable power to keep manufactory running or to power residences. Considering obvious advantages of carbon-based materials, such as abundant sources, low cost and chemical inertness, they show enormous potential as anode materials of SIBs and PIBs. [14-17] Carbon-based materials have different structures (graphite, graphene, hard carbon and soft carbon) and morphologies (0D, 1D, 2D, and 3D, here D represents dimension), [15,18-21] which makes it possible to control these factors of carbon-based materials to meet the demand of highly efficient Na + /K + storage. Graphite delivers two different Na + /K + storage behaviors with theoretical capacities of 35 mAh g −1 (Na + intercalation) and 279 mAh g −1 (K + intercalation), and the high theoretical capacity indicates that graphite is a potential candidate for PIBs. [22,23] Due to high specific surface area and abundant defects, graphene materials (except for pristine single-layered As novel "post lithium-ion batteries," sodium-ion batteries/potassium-ion batteries (SIBs/PIBs) are emerging and show bright prospect in large-scale energy storage applications due to abundant Na/K resources. Further benefits of this technology include, its low cost, chemical inertness and safety. Extensive research findings have demonstrated that carbon-based materials are promising candidates for both SIBs and PIBs. Although the two alkali-ion batteries have similar internal components and electrochemical reaction mechanisms, in carbon-based materials the stora...
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